Chemical composition and cytotoxic activity of the leaf essential oil of <Emphasis Type="Italic">Eugenia zuchowskiae</Emphasis> from Monteverde,Costa Rica

The leaf essential oil of Eugenia zuchowskiae from Monteverde, Costa Rica, has been obtained by hydrodistillation and analyzed by GC–MS. The principal constituents of E. zuchowskiae leaf oil were α-pinene (28.3%), β-caryophyllene (13.2%), α-humulene (13.1%), and α-copaene (8.1%). The leaf essential oil of E. zuchowskiae showed pronounced in-vitro cytotoxic activity against MCF-7, MDA-MB-468, and UACC-257 human tumor cell lines. The major components showed cytotoxic activities comparable to doxorubicin (LC₅₀ 14–70 μg/ml).     

Synthesis and polymerization of epoxymethacrylates, 1. Catalysis and kinetics of the addition reaction of methacrylic acid and 2,2-bis[4-(2,3-epoxypropoxy)phenyl]propane

The kinetics of the addition reaction of methacrylic acid (1) and 2,2-bis[4-(2,3-epoxypropoxy)-phenyl]propane catalyzed by tertiary aliphatic amines, aromatic N-heterocycles and quaternary ammonium salts, respectively, was studied in bulk with equimolar amounts of functional groups from room temperature to 120°C. A reaction order of 1,5 with regard to the conversion of epoxy as well as carboxylic groups was observed. This can be explained assuming the formation of an ammonium alkoxide ion pair by the equilibrium reaction of an epoxy group with ammonium carboxylate and the irreversible consecutive reaction of the ion pair with (1) under formation of 2-hydroxyester groups and regeneration of ammonium carboxylate. The reaction rate constants increase linearly with the concentration of the catalyst and increase with increasing basicity of alkylpyridines. The advantage of the aromatic N-heterocyclic catalysts consists in their stability to peroxides which are ingredients of preparations together with the epoxy methacrylate Bis-GMA, e. g. in dental composites and adhesives.     

Functional adaptation: the key to plasticity of cardiovascular "stem" cells?

There is increasing evidence that cells of disparate phenotypes displaying various degrees of proliferative capacity engraft and function heterotopically in adult organisms. Efforts were made to reconcile these findings with the embryologic notions of pluripotent stem or progenitor cell, although the nature of the 'stemness' remained elusive. This topic is particularly important for the cardiovascular system, in which cytotrophoblasts, certain tumor cells, monocytes/macrophages, peritoneal mesothelial cells, and others acquire endothelial properties and/or perform endothelial functions. Here we suggest that this pluripotency reflects a fundamental characteristic of cellular diversity, which is manifested as the adaptive response to a functional pressure exerted by the cell's biochemical and biophysical microenvironments that would drive their differentiation. In this model, differentiation is a dynamic, reversible, and open-ended process where the cells would maintain the flexibility to respond to changing environmental clues with a fine tuning of their structure, a property that was previously called cellular plasticity. Pluripotent adult stem cells that display this property in culture, and, perhaps upon in vivo administration, were described. Therefore, we also suggest that differentiation of stem cells is a form of cellular plasticity within the larger context of functional adaptation, whereas their stemness remains associated with self-renewal.     

FAS and FAS-L expression by tumor cells and lymphocytes in breast carcinomas and their lymph node metastases

FAS receptor (FAS, CD95) and FAS ligand (FAS-L, CD95-L) are complementary members of a particular apoptotic pathway that plays a major role in immune regulation. The activation of FAS-L may trigger cytotoxic mechanisms leading to the death of FAS-expressing cells. Tumor cells and tumor-infiltrating lymphocytes (TIL) may express FAS and FAS-L in various proportions, and their interplay may affect tumor behavior. In the present study, we explored the expression of FAS and FAS-L in 28 mammary carcinomas (19 ductal and 9 lobular) and in their lymph node metastases. The expression of these mediators in immunostained sections was graded and evaluated comparatively between normal and neoplastic mammary epithelium, between tumor cells and TILs, and between mammary carcinoma cells and their lymph node metastases. We demonstrated the coexpression of FAS and FAS-L by breast carcinoma cells and TIL, with FAS expressed more strongly by normal epithelial cells and TIL than tumor cells. FAS-L was better stained on tumor cells than on TIL. There was equal or greater expression of FAS and FAS-L in the primary tumors and their TIL than in the metastatic counterparts. Comparing the expression of FAS with that of FAS-L, we recorded FAS equal or stronger than FAS-L in the primary mammary tumors and the reversal of their expression, FAS-L greater than FAS in the lymph node metastases. These results are consistent with reports of studies with other tumors, suggesting that the upregulated FAS-L indicates an increased ability of tumor cells to induce apoptosis in TIL and in the normal tissues invaded. However, it is understood that the FAS/FAS-L system, although essential for apoptosis, is only a contributing factor to the complex process of tumor invasion and antitumor defense.